LAUSR

Abstract Harvesting solar energy by adding nanoparticles (NPs) to the base fluid is an effective way to improve solar absorption efficiency. However, the plasmonic NPs used in the solar thermal applications are usually some noble metals (such as: Au and Ag) without consideration of economics, making it difficult for actual engineering applications. In this work, 13 kinds of plasmonic materials were considered and compared based on the solar absorption performance of NP. Results show that Cu NP has both great solar absorption performance and low cost. However, Cu is easily oxidized in the air or water. A SiO2 coating is designed around Cu NP to prevent Cu NP from being oxidized. Cu NP can achieve the higher solar absorption ability per unit volume when the radius is 20 nm to 30 nm. In addition, SiO2 coating can enhance the solar absorption performance of Cu NPs and the highest power absorption per unit volume can be obtained when the core-shell ratio of Cu@SiO2 NP is 5/7. Finally, calculation results show that NP agglomeration in the base fluid would further improve the solar absorption performance. This work provides an effective candidate for the engineering utilization of plasmonic NPs in solar thermal applications.